diff --git a/src/agents/anthropic-payload-log.test.ts b/src/agents/anthropic-payload-log.test.ts
index fb3cf18e47d..037093fbbf5 100644
--- a/src/agents/anthropic-payload-log.test.ts
+++ b/src/agents/anthropic-payload-log.test.ts
@@ -29,7 +29,7 @@ describe("createAnthropicPayloadLogger", () => {
       ],
     };
     const streamFn: StreamFn = ((model, __, options) => {
-      options?.onPayload?.(payload, model);
+      options?.onPayload?.(payload);
       return {} as never;
     }) as StreamFn;
 
diff --git a/src/agents/anthropic-payload-log.ts b/src/agents/anthropic-payload-log.ts
index 2eb5d62e770..d80ed551179 100644
--- a/src/agents/anthropic-payload-log.ts
+++ b/src/agents/anthropic-payload-log.ts
@@ -145,7 +145,7 @@ export function createAnthropicPayloadLogger(params: {
           payload: redactedPayload,
           payloadDigest: digest(redactedPayload),
         });
-        return options?.onPayload?.(payload, model);
+        return options?.onPayload?.(payload);
       };
       return streamFn(model, context, {
         ...options,
diff --git a/src/agents/openai-ws-stream.ts b/src/agents/openai-ws-stream.ts
index 307812e6be5..04550a665f4 100644
--- a/src/agents/openai-ws-stream.ts
+++ b/src/agents/openai-ws-stream.ts
@@ -797,7 +797,7 @@ export function createOpenAIWebSocketStreamFn(
         ...(prevResponseId ? { previous_response_id: prevResponseId } : {}),
         ...extraParams,
       };
-      const nextPayload = options?.onPayload?.(payload, model);
+      const nextPayload = options?.onPayload?.(payload);
       const requestPayload = (nextPayload ?? payload) as Parameters<
         OpenAIWebSocketManager["send"]
       >[0];
diff --git a/src/agents/pi-embedded-runner-extraparams.test.ts b/src/agents/pi-embedded-runner-extraparams.test.ts
index 7a29f30f9eb..6bbc3550370 100644
--- a/src/agents/pi-embedded-runner-extraparams.test.ts
+++ b/src/agents/pi-embedded-runner-extraparams.test.ts
@@ -210,7 +210,7 @@ describe("applyExtraParamsToAgent", () => {
   }) {
     const payload = params.payload ?? { store: false };
     const baseStreamFn: StreamFn = (model, _context, options) => {
-      options?.onPayload?.(payload, model);
+      options?.onPayload?.(payload);
       return {} as ReturnType<StreamFn>;
     };
     const agent = { streamFn: baseStreamFn };
@@ -236,7 +236,7 @@ describe("applyExtraParamsToAgent", () => {
   }) {
     const payload = params.payload ?? {};
     const baseStreamFn: StreamFn = (model, _context, options) => {
-      options?.onPayload?.(payload, model);
+      options?.onPayload?.(payload);
       return {} as ReturnType<StreamFn>;
     };
     const agent = { streamFn: baseStreamFn };
diff --git a/src/agents/pi-embedded-runner/anthropic-stream-wrappers.ts b/src/agents/pi-embedded-runner/anthropic-stream-wrappers.ts
index efed941762d..3b91760c006 100644
--- a/src/agents/pi-embedded-runner/anthropic-stream-wrappers.ts
+++ b/src/agents/pi-embedded-runner/anthropic-stream-wrappers.ts
@@ -319,7 +319,7 @@ export function createAnthropicToolPayloadCompatibilityWrapper(
             );
           }
         }
-        return originalOnPayload?.(payload, model);
+        return originalOnPayload?.(payload);
       },
     });
   };
diff --git a/src/agents/pi-embedded-runner/extra-params.kilocode.test.ts b/src/agents/pi-embedded-runner/extra-params.kilocode.test.ts
index 35a6cefcbd4..4da5cc866a5 100644
--- a/src/agents/pi-embedded-runner/extra-params.kilocode.test.ts
+++ b/src/agents/pi-embedded-runner/extra-params.kilocode.test.ts
@@ -97,7 +97,7 @@ describe("extra-params: Kilocode kilo/auto reasoning", () => {
 
     const baseStreamFn: StreamFn = (model, _context, options) => {
       const payload: Record<string, unknown> = { reasoning_effort: "high" };
-      options?.onPayload?.(payload, model);
+      options?.onPayload?.(payload);
       capturedPayload = payload;
       return createAssistantMessageEventStream();
     };
@@ -125,7 +125,7 @@ describe("extra-params: Kilocode kilo/auto reasoning", () => {
 
     const baseStreamFn: StreamFn = (model, _context, options) => {
       const payload: Record<string, unknown> = {};
-      options?.onPayload?.(payload, model);
+      options?.onPayload?.(payload);
       capturedPayload = payload;
       return createAssistantMessageEventStream();
     };
@@ -158,7 +158,7 @@ describe("extra-params: Kilocode kilo/auto reasoning", () => {
 
     const baseStreamFn: StreamFn = (model, _context, options) => {
       const payload: Record<string, unknown> = { reasoning_effort: "high" };
-      options?.onPayload?.(payload, model);
+      options?.onPayload?.(payload);
       capturedPayload = payload;
       return createAssistantMessageEventStream();
     };
diff --git a/src/agents/pi-embedded-runner/extra-params.openrouter-cache-control.test.ts b/src/agents/pi-embedded-runner/extra-params.openrouter-cache-control.test.ts
index 5a36c9c5a4d..a5b9940279f 100644
--- a/src/agents/pi-embedded-runner/extra-params.openrouter-cache-control.test.ts
+++ b/src/agents/pi-embedded-runner/extra-params.openrouter-cache-control.test.ts
@@ -13,7 +13,7 @@ type StreamPayload = {
 
 function runOpenRouterPayload(payload: StreamPayload, modelId: string) {
   const baseStreamFn: StreamFn = (model, _context, options) => {
-    options?.onPayload?.(payload, model);
+    options?.onPayload?.(payload);
     return createAssistantMessageEventStream();
   };
   const agent = { streamFn: baseStreamFn };
diff --git a/src/agents/pi-embedded-runner/extra-params.ts b/src/agents/pi-embedded-runner/extra-params.ts
index a9d5085e013..e5fe0b2a19f 100644
--- a/src/agents/pi-embedded-runner/extra-params.ts
+++ b/src/agents/pi-embedded-runner/extra-params.ts
@@ -235,7 +235,7 @@ function createGoogleThinkingPayloadWrapper(
             thinkingLevel,
           });
         }
-        return onPayload?.(payload, model);
+        return onPayload?.(payload);
       },
     });
   };
@@ -268,7 +268,7 @@ function createZaiToolStreamWrapper(
           // Inject tool_stream: true for Z.AI API
           (payload as Record<string, unknown>).tool_stream = true;
         }
-        return originalOnPayload?.(payload, model);
+        return originalOnPayload?.(payload);
       },
     });
   };
@@ -315,7 +315,7 @@ function createParallelToolCallsWrapper(
         if (payload && typeof payload === "object") {
           (payload as Record<string, unknown>).parallel_tool_calls = enabled;
         }
-        return originalOnPayload?.(payload, model);
+        return originalOnPayload?.(payload);
       },
     });
   };
diff --git a/src/agents/pi-embedded-runner/extra-params.zai-tool-stream.test.ts b/src/agents/pi-embedded-runner/extra-params.zai-tool-stream.test.ts
index f7262a66798..2dab69cd15a 100644
--- a/src/agents/pi-embedded-runner/extra-params.zai-tool-stream.test.ts
+++ b/src/agents/pi-embedded-runner/extra-params.zai-tool-stream.test.ts
@@ -22,7 +22,7 @@ type ToolStreamCase = {
 function runToolStreamCase(params: ToolStreamCase) {
   const payload: Record<string, unknown> = { model: params.model.id, messages: [] };
   const baseStreamFn: StreamFn = (model, _context, options) => {
-    options?.onPayload?.(payload, model);
+    options?.onPayload?.(payload);
     return {} as ReturnType<StreamFn>;
   };
   const agent = { streamFn: baseStreamFn };
diff --git a/src/agents/pi-embedded-runner/moonshot-stream-wrappers.ts b/src/agents/pi-embedded-runner/moonshot-stream-wrappers.ts
index c066a168a0f..7eca8c17dbd 100644
--- a/src/agents/pi-embedded-runner/moonshot-stream-wrappers.ts
+++ b/src/agents/pi-embedded-runner/moonshot-stream-wrappers.ts
@@ -89,7 +89,7 @@ export function createSiliconFlowThinkingWrapper(baseStreamFn: StreamFn | undefi
             payloadObj.thinking = null;
           }
         }
-        return originalOnPayload?.(payload, model);
+        return originalOnPayload?.(payload);
       },
     });
   };
@@ -139,7 +139,7 @@ export function createMoonshotThinkingWrapper(
             }
           }
         }
-        return originalOnPayload?.(payload, model);
+        return originalOnPayload?.(payload);
       },
     });
   };
diff --git a/src/agents/pi-embedded-runner/openai-stream-wrappers.ts b/src/agents/pi-embedded-runner/openai-stream-wrappers.ts
index d0b483e83ec..32f998ffc46 100644
--- a/src/agents/pi-embedded-runner/openai-stream-wrappers.ts
+++ b/src/agents/pi-embedded-runner/openai-stream-wrappers.ts
@@ -281,7 +281,7 @@ export function createOpenAIResponsesContextManagementWrapper(
             compactThreshold,
           });
         }
-        return originalOnPayload?.(payload, model);
+        return originalOnPayload?.(payload);
       },
     });
   };
@@ -335,7 +335,7 @@ export function createOpenAIServiceTierWrapper(
             payloadObj.service_tier = serviceTier;
           }
         }
-        return originalOnPayload?.(payload, model);
+        return originalOnPayload?.(payload);
       },
     });
   };
diff --git a/src/agents/pi-embedded-runner/proxy-stream-wrappers.ts b/src/agents/pi-embedded-runner/proxy-stream-wrappers.ts
index 4f77c31cfdd..a5f9f5b1d85 100644
--- a/src/agents/pi-embedded-runner/proxy-stream-wrappers.ts
+++ b/src/agents/pi-embedded-runner/proxy-stream-wrappers.ts
@@ -92,7 +92,7 @@ export function createOpenRouterSystemCacheWrapper(baseStreamFn: StreamFn | unde
             }
           }
         }
-        return originalOnPayload?.(payload, model);
+        return originalOnPayload?.(payload);
       },
     });
   };
@@ -113,7 +113,7 @@ export function createOpenRouterWrapper(
       },
       onPayload: (payload) => {
         normalizeProxyReasoningPayload(payload, thinkingLevel);
-        return onPayload?.(payload, model);
+        return onPayload?.(payload);
       },
     });
   };
@@ -138,7 +138,7 @@ export function createKilocodeWrapper(
       },
       onPayload: (payload) => {
         normalizeProxyReasoningPayload(payload, thinkingLevel);
-        return onPayload?.(payload, model);
+        return onPayload?.(payload);
       },
     });
   };
diff --git a/src/agents/pi-embedded-runner/run/attempt.ts b/src/agents/pi-embedded-runner/run/attempt.ts
index 3457fdf0161..1b12310de3a 100644
--- a/src/agents/pi-embedded-runner/run/attempt.ts
+++ b/src/agents/pi-embedded-runner/run/attempt.ts
@@ -413,14 +413,14 @@ export function wrapOllamaCompatNumCtx(baseFn: StreamFn | undefined, numCtx: num
       ...options,
       onPayload: (payload: unknown) => {
         if (!payload || typeof payload !== "object") {
-          return options?.onPayload?.(payload, model);
+          return options?.onPayload?.(payload);
         }
         const payloadRecord = payload as Record<string, unknown>;
         if (!payloadRecord.options || typeof payloadRecord.options !== "object") {
           payloadRecord.options = {};
         }
         (payloadRecord.options as Record<string, unknown>).num_ctx = numCtx;
-        return options?.onPayload?.(payload, model);
+        return options?.onPayload?.(payload);
       },
     });
 }